With the substantial growth in demand for internet bandwidth, internet traffic requirements have become quite unpredictable. In adapting to this challenge, many networks have evolved to use reconfigurable optical add drop modules (ROADM) at nodes in ring and mesh networks. These networks require the use of wavelength switch systems (WSS). Traffic from point A to point B can be routed dynamically through the use of these networks. To enable routing flexibility, these systems employ many usable wavelengths and channels. When needed, a new channel can be deployed in response to an increased bandwidth requirement, or alternatively a channel can be dropped in response to congestion or disruption of part of the network. The evolution of WSS in response to these growing needs involve two basic architectures: colored WSS and colorless WSS.
The colored WSS will switch a specific wavelength to an associated output fiber. The colored WSS was developed using arrayed waveguide gratings (AWG) as a wavelength multiplexer/de-multiplexer element. The drawback of the colored WSS is that it fails to provide flexibility because fixed or specific wavelengths are needed in order for the switching process to occur, even though tunable lasers are widely available. The wavelength is fixed due to the physical association between the wavelength and a particular output fiber. This limits the ability of a colored WSS to act as an add/drop module because fixed or specified wavelengths are necessary in order to perform the add/drop functions. Using a colored WSS creates an inflexible ROADM and network. The wavelength provisions or routing determinations are made when the WSS is installed, which is a manual rather than dynamic operation.
The colorless WSS, on the other hand, provides the freedom of choosing any wavelength transmission dynamically, provided that tunable lasers are connected to the WSS. However, each tunable laser can only transmit data via one channel of the WSS. If more wavelengths are needed from a node, more tunable lasers will need to be connected to the WSS. In order to connect more tunable lasers to the WSS, more WSS ports are needed. For this reason, it is desirable to have a WSS with a higher port count, or an optical architecture configured to transmit a greater number of multi-channel optical signals using the existing number of ports.
There is a need in the art of optical switching for an optical switch architecture that can increase the flexibility of a wavelength switch system while retaining the majority of its design aspects.
It is within this context that embodiments of the present invention arise.